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mtd: devices: elm: Low power transition support
ELM is used for locating bit-flip errors in when using BCH ECC scheme. This patch adds suspend/resume support for leaf level ELM driver, And also provides ELM register context save & restore support, so that configurations are preserved across hardware power-off/on transitions. Signed-off-by: Philip Avinash <avinashphilip@ti.com> Signed-off-by: Pekon Gupta <pekon@ti.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
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1 changed files with 117 additions and 0 deletions
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@ -20,14 +20,21 @@
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/of.h>
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#include <linux/sched.h>
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#include <linux/pm_runtime.h>
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#include <linux/platform_data/elm.h>
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#define ELM_SYSCONFIG 0x010
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#define ELM_IRQSTATUS 0x018
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#define ELM_IRQENABLE 0x01c
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#define ELM_LOCATION_CONFIG 0x020
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#define ELM_PAGE_CTRL 0x080
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#define ELM_SYNDROME_FRAGMENT_0 0x400
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#define ELM_SYNDROME_FRAGMENT_1 0x404
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#define ELM_SYNDROME_FRAGMENT_2 0x408
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#define ELM_SYNDROME_FRAGMENT_3 0x40c
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#define ELM_SYNDROME_FRAGMENT_4 0x410
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#define ELM_SYNDROME_FRAGMENT_5 0x414
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#define ELM_SYNDROME_FRAGMENT_6 0x418
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#define ELM_LOCATION_STATUS 0x800
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#define ELM_ERROR_LOCATION_0 0x880
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@ -56,12 +63,27 @@
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#define SYNDROME_FRAGMENT_REG_SIZE 0x40
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#define ERROR_LOCATION_SIZE 0x100
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struct elm_registers {
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u32 elm_irqenable;
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u32 elm_sysconfig;
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u32 elm_location_config;
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u32 elm_page_ctrl;
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u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
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u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
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};
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struct elm_info {
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struct device *dev;
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void __iomem *elm_base;
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struct completion elm_completion;
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struct list_head list;
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enum bch_ecc bch_type;
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struct elm_registers elm_regs;
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};
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static LIST_HEAD(elm_devices);
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@ -384,6 +406,100 @@ static int elm_remove(struct platform_device *pdev)
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return 0;
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}
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/**
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* elm_context_save
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* saves ELM configurations to preserve them across Hardware powered-down
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*/
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static int elm_context_save(struct elm_info *info)
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{
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struct elm_registers *regs = &info->elm_regs;
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enum bch_ecc bch_type = info->bch_type;
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u32 offset = 0, i;
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regs->elm_irqenable = elm_read_reg(info, ELM_IRQENABLE);
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regs->elm_sysconfig = elm_read_reg(info, ELM_SYSCONFIG);
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regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
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regs->elm_page_ctrl = elm_read_reg(info, ELM_PAGE_CTRL);
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for (i = 0; i < ERROR_VECTOR_MAX; i++) {
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offset = i * SYNDROME_FRAGMENT_REG_SIZE;
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switch (bch_type) {
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case BCH8_ECC:
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regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
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ELM_SYNDROME_FRAGMENT_3 + offset);
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regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
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ELM_SYNDROME_FRAGMENT_2 + offset);
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case BCH4_ECC:
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regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
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ELM_SYNDROME_FRAGMENT_1 + offset);
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regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
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ELM_SYNDROME_FRAGMENT_0 + offset);
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default:
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return -EINVAL;
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}
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/* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
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* to be saved for all BCH schemes*/
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regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
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ELM_SYNDROME_FRAGMENT_6 + offset);
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}
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return 0;
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}
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/**
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* elm_context_restore
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* writes configurations saved duing power-down back into ELM registers
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*/
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static int elm_context_restore(struct elm_info *info)
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{
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struct elm_registers *regs = &info->elm_regs;
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enum bch_ecc bch_type = info->bch_type;
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u32 offset = 0, i;
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elm_write_reg(info, ELM_IRQENABLE, regs->elm_irqenable);
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elm_write_reg(info, ELM_SYSCONFIG, regs->elm_sysconfig);
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elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
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elm_write_reg(info, ELM_PAGE_CTRL, regs->elm_page_ctrl);
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for (i = 0; i < ERROR_VECTOR_MAX; i++) {
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offset = i * SYNDROME_FRAGMENT_REG_SIZE;
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switch (bch_type) {
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case BCH8_ECC:
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elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
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regs->elm_syndrome_fragment_3[i]);
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elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
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regs->elm_syndrome_fragment_2[i]);
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case BCH4_ECC:
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elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
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regs->elm_syndrome_fragment_1[i]);
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elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
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regs->elm_syndrome_fragment_0[i]);
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default:
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return -EINVAL;
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}
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/* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
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elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
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regs->elm_syndrome_fragment_6[i] &
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ELM_SYNDROME_VALID);
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}
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return 0;
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}
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static int elm_suspend(struct device *dev)
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{
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struct elm_info *info = dev_get_drvdata(dev);
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elm_context_save(info);
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pm_runtime_put_sync(dev);
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return 0;
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}
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static int elm_resume(struct device *dev)
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{
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struct elm_info *info = dev_get_drvdata(dev);
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pm_runtime_get_sync(dev);
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elm_context_restore(info);
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return 0;
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}
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static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);
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#ifdef CONFIG_OF
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static const struct of_device_id elm_of_match[] = {
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{ .compatible = "ti,am3352-elm" },
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@ -397,6 +513,7 @@ static struct platform_driver elm_driver = {
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.name = "elm",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(elm_of_match),
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.pm = &elm_pm_ops,
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},
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.probe = elm_probe,
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.remove = elm_remove,
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